API 5L (American Petroleum Institute standard) is the authoritative specification for oil and gas transmission pipelines worldwide. The Grade B specification, as a commonly used grade, sets stringent requirements for chemical composition and mechanical properties. The seamless pipe of Grade B must have a carbon content controlled below 0.22% and a manganese content of 1.2%-1.5%, while requiring a tensile strength of ≥415 MPa and a yield strength of ≥240 MPa. This balanced chemical composition gives the pipeline good weldability and mechanical strength, enabling it to withstand working pressures above 6.3 MPa and meet the transmission requirements of most onshore pipelines.
API 5L GRB Seamless Steel Pipes, API 5L GRB Welded Pipes Chemical Composition
| Chemical Composition % | ||||||||
| PSL1 | PSL2 | |||||||
| Grade | C (Max.) | Mn(Max.) | P(Max.) | S(Max.) | C (Max.) | Mn(Max.) | P(Max.) | S(Max.) |
| B | 0.26 | 1.20 | 0.03 | 0.03 | 0.22 | 1.30 | 0.025 | 0.015 |
API 5L GRB Seamless Steel Pipes, API 5L GRB Welded Pipes Mechanical Properties
| Mechanical Properties PSL 1 | |||||
| Grade | Yield Strength(Min.) | Tensile Strength(Min.) | Elongation | ||
| Ksi | MPa | Ksi | MPa | E=1944 A 0.2 /U 0.9 | |
| B | 35 | 241 | 60 | 414 | |
API 5L GRB V.S. API 5L X42 Line Pipe
| Comparison Item | API 5L Grade B | API 5L X42 |
|---|---|---|
| Grade Level | Basic pipeline steel (PSL1/PSL2) | High-strength pipeline steel (mainly PSL2) |
| Yield Strength | ≥240 MPa | ≥290 MPa (20% higher) |
| Tensile Strength | 415-655 MPa | 415-760 MPa |
| Min Operating Temp | -46°C (PSL2) | -60°C (PSL2) |
| Low-Temp Impact Energy | -30°C: ≥27J | -46°C: ≥40J |
| Max Carbon Equivalent | 0.43% | 0.43% |
| Economic Pressure Range | ≤6.3 MPa (e.g., city gas networks) | 6.3-10 MPa (long-distance trunk lines) |
| Wall Thinning Rate | - | 12% thinner than Grade B (at same pressure) |
| H₂S Resistance Limit | ≤120°C (per NACE MR0175) | ≤120°C (requires X42S acid-resistant variant) |
| Cost Premium | Base price | +15%~20% |
